A Combined Anatomical and Clinical Study for Quantitative Analysis of the Microcirculation in the Classic Perfusion Zones of the Deep Inferior Epigastric Artery Perforator Flap

Abstract

Sir:FigureWe read with interest the article by Rahmanian-Schwarz et al., “A Combined Anatomical and Clinical Study for Quantitative Analysis of the Microcirculation in the Classic Perfusion Zones of the Deep Inferior Epigastric Artery Perforator Flap.”1 Although the study itself is well designed and well reported, and certainly adds some valuable anatomical and physiologic information to our understanding of deep inferior epigastric artery (DIEA) perforator (DIEP) flaps, we would like to comment on the terminology used in the mapping of perfusion zones of the lower abdominal wall. The authors make the statement that “since the description of the vascular territories of the DIEP flap was published in 1983, many surgeons have used it for the selection of well-perfused tissue in microvascular autologous breast reconstruction. Our study disputes a generally accepted definition of the classic perfusion zones of the DIEP flap.” In making this statement, the authors appear to have confused the previously described perfusion zones of the transverse rectus abdominis myocutaneous (TRAM) flap with the DIEP flap. The TRAM flap perfusion zones are based on skin perfusion by means of all the cutaneous perforators of the DIEA, whereas a DIEP flap is necessarily perfused by only one or several perforators. The terminology in the recent literature has thus changed from the TRAM perfusion zones (or the angiosome of the DIEA) to the DIEP perfusion zones (or the perforator angiosome of DIEA perforators), based on a range of cadaveric and clinical studies performed by both ourselves and by Wong et al. and Saint-Cyr et al.2–4 When describing the perfusion of the abdominal wall based on one or several perforators, the perfusion zones are markedly different from the TRAM perfusion zones. In our clinical and cadaveric studies,2 in which we looked at 200 hemiabdominal walls from both cadavers and patients, analyzing over 1500 DIEA perforators, we found that there is a specific “perforator” angiosome for each individual perforator, and that these differ between medial and lateral row perforators. “Perforator angiosomes” mirror the angiosome patterns described by Taylor and Palmer5; however, the subangiosomes of individual perforators present some unique features. We found that each DIEA perforator has its own territory of supply, independent of the zone of supply by the source vessel. Of these, lateral row perforators and medial row perforators have fundamental differences in their zones of perfusion. Figure 1 demonstrates the perforator angiosomes of the DIEP flap, with several key features evident: Zone I of medial row perforators is larger, has more extensive branching, and has larger caliber vessels than lateral row perforators. Zone I of medial row perforators is centered over the position of perforators as they emerge from the anterior rectus sheath, as they have a relatively direct course to the Scarpa fascia, at which point branching occurs; whereas zone I of lateral row perforators is centered lateral to the location of the perforator at the anterior rectus sheath, as there is a lengthy lateral course traversed by lateral row perforators before reaching the Scarpa fascia and branching. The primary zones (zones I and II) of medial row perforators routinely cross the midline to perfuse the medial parts of the contralateral hemiabdominal wall, whereas lateral row perforators do not primarily communicate with branches that cross the midline. Zones I and II (the territories of maximal perfusion within a perforator flap) comprise more than the entire ipsilateral hemiabdomen for a medial row perforator, but are more limited for a lateral row perforator. Fig. 1: The perforator perfusion zones. Perfusion zones of the lower abdominal flap are supplied by a medial row perforator (red arrow, above) or a lateral row perforator (red arrow, below). (Reproduced with permission from Rozen WM, Ashton MW, Le Roux CM, Pan WR, Corlett RJ. The perforator angiosome: A new concept in the design of deep inferior epigastric artery perforator flaps for breast reconstruction. Microsurgery 2010;30:1–7.)These findings match similar studies by Wong et al., and a close look at the results of the current study demonstrate that Rahmanian-Schwarz et al. have similar findings themselves: the perfusion studies in their Figure 6 demonstrate very nicely the “perforator angiosome” of a single perforator—shown nicely to not fill an entire TRAM flap zone. Warren M. Rozen, M.B.B.S., B.Med.Sc., Ph.D. Iain S. Whitaker, M.A.Cantab., M.B.B.Chir., Ph.D. Mark W. Ashton, M.B.B.S., M.D. Jack Brockhoff Reconstructive Plastic Surgery Research Unit, Department of Anatomy, University of Melbourne, Parkville, Victoria, Australia